Synthesis of glucagon-like peptide

Method of manufacturing a GLP-1 or GLP-1 agonist peptide, wherein said peptide comprises:

• A-(R1)x-(R2)y-R3-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-R8-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-R4-R5-(R6)w-(R7)z-B (SEQ ID NO:
• 1)
• or is of formula
• A-(R1)x-(R2)y-R3-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-B (SEQ ID NO:
• 2)
• or is of formula
• A-(R1)x-(R2)y-R3-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-B (SEQ ID NO:
• 3)
• or is of formula
• A-(R1)x-(R2)y-R3-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-B (SEQ ID NO:
• 4)
• or is of formula
• A-(R1)x-(R2)y-R3-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-R8-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-R4-B (SEQ ID NO:
• 5)
• or is of formula
• A-(R1)x-(R2)y-R3-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-R8-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-R4-Gly-B (SEQ ID NO:
• 6)
• wherein
• B=—OH or —NH2;
• A=H-, Ac-, Boc-, Fmoc-;
• R1=His, D-His, desamino-histidine, 2-amino-histidine, β-hydroxy-histidine, homohistidine, alpha-fluoromethyl-histidine or alpha-methyl-histidine;
• R2=Ala, D-Ala, Val, D-Val, Gly, Aib (α-aminoisobutyric acid);
• R3=Glu, Asp, Met, Leu;
• R4=Lys or Arg;
• R5=Gly, Aib, Ala, D-Ala;
• R6=Arg, Lys or Gly;
• R7=Arg, Lys or Gly;
• R8=Gly or Aib
• and wherein, independently, x, y, w, z are 0 or 1, with the proviso that y=1 where x=1 and with the proviso that w=1 where z=1, and further wherein individual amino acids may optionally carry protection groups, comprising the steps of
• a) synthesizing the peptide on a solid phase by stepwise coupling of Fmoc-protected, amino acids or dipeptides comprising pseudoproline dipeptides, in a linear fashion, with the proviso that at one suitable sequence position, which is Val-Ser- or Val-Ser-Ser, a first pseudoproline dipeptide is coupled to the growing peptide chain,
• wherein the pseudoproline dipeptide is selected from the group consisting of Fmoc-Val-Ser(ψMe,Mepro)-OH, Fmoc-Val-Ser(ψH,Hpro)-OH, Fmoc-Ser(P)-Ser(ψMe,Mepro)-OH and Fmoc-Ser(P)-Ser(ψH,Hpro)-OH, wherein P is an acid-cleavable protection group that is cleaved under strongly acidic condition of at least 80% TFA, and
• b) cleaving the peptide from the solid phase, and deprotecting the peptide chain with at least 80% TFA.